Chloroprene polymers have had great utility as rubbers. However, because of the extremely fast polymerization rates of chloroprene monomers, processes for polymerizing chloropene monomers have been difficult to control. Moreover, the high heat of polymerization has made it difficult to control the properties of the chloroprene polymers in particular the molecular structure and the particle properties. Emulsion processes have been used to produce relatively small particles, i.e., less than 0.15 microns in diameter which have been used extensively in paints and coatings. These products usually require small particles to insure emulsion stability and dispersibility.
Chlorprene rubbers are known to be fire-resistant and can be incorporated in compositions to insure self-extinguishing properties. Being rubbers they can be used in thermoplastic polyblends as a rubber phase for added toughness. Such uses of chloroprene polymers require closely controlled properties in the rubber, particularly the particle size parameters. Tough polyblends require larger particles than those produced by the known commerical emulsion processes. Sophisticated engineering properties can only be obtained by using polychloroprene particles that are controlled as to average particle size and particle size distribution. Prior art emulsion processes have been found to be grossly deficient in meeting these requirements.
Accordingly, it is an objective of the present invention to provide a polymerization process that can produce large chloroprene polymer particles having a predetermined weight average particle diameter and a narrow particle size distribution wherein the diameter of the particle size is in the range of from 0.15 to 2.0 microns.
It is also an object of this invention to provide a process with a high level of reproducibility that can provide stable aqueous dispersions of large chloroprene polymer particles having substantially monodisperse particle size distributions.